JP4939818B2 - Pneumatic tires for motorcycles - Google Patents

Description

  The present invention includes at least a pair of circumferential grooves that extend substantially in the tire circumferential direction and are located across the tire equatorial plane in the tread portion, and the tire circumferential direction from the tire width direction outer side to the tire width direction inner side of the tread portion ground contact surface Pneumatic tire for motorcycles having a plurality of inclined grooves extending in a direction inclined with respect to the direction and terminating in the tread surface, and particularly suitable for application to the front wheels of racing motorcycles In particular, the lightness of handling of such tires and the stability performance during braking are compatible at a high level.

  As a pneumatic tire for a motorcycle having such a tread pattern, for example, those described in Patent Documents 1 and 2 are known. The tire described in Patent Document 1 forms a circumferential groove extending intermittently on the crown center in the tread of the tire, forming an inclined groove extending obliquely from one end of the circumferential groove toward the shoulder portion, The angle formed by the inclined groove with respect to the crown center is 40 to 60 °. In addition, the tire described in Patent Document 2 has a total of three circumferential grooves on the crown center and both sides thereof, and inclined grooves extending across these circumferential grooves. Is set to 70 to 100% of the depth of the inclined groove.

Japanese Patent Laid-Open No. 2-28066 JP-A-6-115316

  Tires with inclined grooves in the tread can be expected to improve handling ease, but are stable in situations where sudden input is applied to the tires, such as braking in front of corners during racing. Is lacking. In general, in order to ensure the stability of the tire, it is effective to reduce the tire width direction rigidity of the tread part and increase the tire behavior in the process where the input to the tire increases and the contact surface of the tread part increases. . However, in the tire described in Patent Document 1, the circumferential groove is arranged in the central region of the tread portion so as to be continuous with the inclined groove, and the rigidity in the tire width direction of the tread portion is reduced. There is no change in the rigidity in the tire width direction in the process of increasing the contact surface, and the effect is less effective in improving the stability performance. In the tire described in Patent Document 2, a total of three circumferential grooves, one in the center region of the tread portion and one in each side region of the tread portion, are arranged, and the tread portion ground contact surface increases. However, since the tire width direction rigidity is lowered, since the circumferential groove is also provided in the central area of the tread portion, the rigidity of the tread portion ground contact surface is excessively lowered, and as a result, the stability performance is not improved. That is, conventionally, there has been no tread pattern that can improve handling stability while improving braking stability.

  The object of the present invention is to solve such problems of the prior art, and the purpose of the invention is to improve the lightness of handling by optimizing the pattern arrangement and to improve the braking. It is an object to provide a pneumatic tire for a motorcycle that can improve the stability performance at the time.

In order to achieve the above object, the present invention provides a tire that extends from the outer side in the tire width direction of the tread portion ground surface to the tread portion, extending at least in the tire circumferential direction and positioned between the tire equatorial plane. In a pneumatic tire for a motorcycle having a plurality of inclined grooves that extend inward in the width direction with respect to the tire circumferential direction and terminate in the tread portion ground contact surface, the tread portion is defined as a central region. When divided into two lateral regions sandwiched on both sides, the circumferential grooves are located in the lateral regions, and inclined grooves that are inclined in the opposite direction to the tire circumferential direction alternate along the tire circumferential direction. The inclined groove that is arranged in the same direction with respect to the tire circumferential direction is seen in the tire circumferential direction, crosses the circumferential groove, and further slopes that cross the tire equatorial plane and the slope that does not cross the circumferential groove Groove and A pneumatic tire for a motorcycle, wherein the are arranged alternately.

  The “substantially tire circumferential direction” here refers to a direction within an angle of 0 to 10 ° with the tire circumferential direction. The “central area” of the tread portion refers to a region including the tire equator plane, and preferably refers to a region having a width equal to or less than 50% of the creeping width of the tread portion ground contact surface with the tire equator plane as the center. In addition, the “side region” is a region located outside the center region in the tire width direction and including the tread ground contact edge. Further, “inclined in the opposite direction to the tire circumferential direction” means an angle formed by the tire circumferential direction and the inclined groove, assuming orthogonal coordinates with the tire circumferential direction as the x axis and the tire width direction as the y axis. Among them, the acute angle is in the first quadrant and the third quadrant in one inclined groove, and the relationship is in the second quadrant and the fourth quadrant in the other inclined groove.

  In addition, the central region has a width of 10% of the creepage width of the tread portion ground contact surface centered on the tire equator surface, the circumferential groove is a pair or two pairs, and the circumferential groove is a tread centering on the tread ground contact end. It is preferable that it is located in a region having a width of 30% of the creeping width of the partial grounding surface, and that the inclined groove has a linear or arcuate extending shape.

  Furthermore, the tire according to the present invention is a directional tire in which the rotation direction when the vehicle is mounted is specified, and the inclined groove has an inner end in the tire width direction that enters the tread portion ground contact surface preceding the outer end in the tire width direction. Is preferred.

  In addition, the tire of the present invention is preferably a front wheel tire mounted on a front wheel of a motorcycle.

  According to this invention, by optimizing the pattern arrangement of the tread portion, it is possible to provide a pneumatic tire for a motorcycle that can improve the lightness of handling and improve the stability during braking. Become.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view in the tire width direction of a typical motorcycle pneumatic tire (hereinafter referred to as “tire”) according to the present invention, and FIG. 2 is a partial development view showing a pattern of a typical tread portion. .

  A tire 1 shown in FIG. 1 includes a pair of bead portions 3 in which bead cores 2 are embedded, a pair of sidewall portions 4 that are continuous to the outside of the bead portion 3 in the tire radial direction, and a tread portion 5 that extends between the sidewall portions. With Further, in the tire 1, a carcass 6 extending in a toroidal shape between both bead cores and a belt layer positioned on the outer periphery of the crown portion of the carcass 6 are embedded.

  As shown in FIG. 2, the tread portion 5 extends substantially in the tire circumferential direction and has a pair of circumferential grooves 7 located in the left and right half regions across the tire equatorial plane CL, and a direction inclined in the tire circumferential direction. A plurality of inclined grooves 8 extending in the direction are arranged. The inclined groove 8 extends from the outer side in the tire width direction of the tread portion grounding surface toward the inner side in the tire width direction, and terminates in the tread portion grounding surface, that is, one end portion is outside the tread portion grounding surface. The other end portion is present in the tread portion grounding surface without opening to another groove.

  The circumferential groove 7 divides the tread portion 5 of the tire 1 into a central region 9 including the tire equatorial plane CL, and a side region 10 located on both sides of the central region 9 and including the tread grounding end TE. It is arrange | positioned in the side area 10 at the time of doing. The inventor repeated earnest research on the stability performance of pneumatic tires for motorcycles, and by braking from a straight running state, when the input to the tire increases and the tread part ground contact surface increases, A change in rigidity of the side region 10 of the tread portion 5 has a great influence on stability. On the other hand, if a circumferential groove is present in the central region 9, the rigidity of the tread portion ground contact surface is excessively lowered, and instead the tire We obtained the knowledge that the stability performance of was reduced. Based on such knowledge, in the tire of the present invention, high stability is ensured by disposing the circumferential groove 7 only in the lateral region 10.

Further, as for the inclined groove 8, a groove inclined in the opposite direction with respect to the tire circumferential direction, and in the embodiment shown in FIG. 1, a right-lowering groove and a left-lowering groove are alternately arranged along the tire circumferential direction. is doing. As a result, when turning in either the left or right direction, since the inclined groove follows the input from the road surface, the lightness of the handling performance is improved .

Furthermore, half of the inclined grooves cross the circumferential groove 7 and further extend beyond the tire equatorial plane CL to the opposite half area, so that the rigidity of the tread portion 5 is ensured, and all In the camber area, the lightness of handling performance can be improved.

  Further, a region having a width of 10% of the creepage width LT of the tread portion ground contact surface with the tire equatorial plane CL as the center is subjected to a particularly large shearing force during braking. Therefore, if there is a circumferential groove in this region, the tread portion The rigidity of 5 is too low, and on the contrary, the stability performance is reduced. Therefore, it is preferable that the central region 9 has a width of 10% of the creeping width LT of the tread portion ground contact surface with the tire equatorial plane CL as the center, and the circumferential groove 7 is disposed on the outer side in the tire width direction.

  The number of circumferential grooves can be changed as appropriate according to the tire size, usage environment, etc., but in the case of a pneumatic tire for a motorcycle having a general size, it may be a pair or two pairs. preferable. The reason for this is that when the number of pairs exceeds two, the rigidity of the tread portion 5 is excessively decreased, and the stability performance is decreased.

  Further, the circumferential groove 7 is located in a region having a width of 30% of the creeping width LT of the tread portion grounding surface with the tread grounding end TE as the center, that is, the groove width center position between the tread grounding end TE and the circumferential groove 7. The distance RD in the tire width direction measured along the contact surface of the tread portion 5 is preferably 15% or less of the tread surface width LT. The portion where the ground contact surface of the tread portion 5 increases due to braking is in a region within 15% of the tread creeping width LT with the tread ground contact TE as the center. By arranging the circumferential groove 7 in this region, the tread is provided. The effect of improving the stability can be obtained effectively by relieving the shear force change of the part.

  As shown in FIG. 2, the circumferential groove 8 can have a linearly extending shape, but as shown in FIG. 3, it can also have an arcuately extending shape. The arc-shaped circumferential groove is particularly effective in suppressing uneven wear because the groove is arranged in a direction along the input to the tire when the corner rises.

  Further, the tire 1 is a directional tire in which the rotation direction when the vehicle is mounted is specified, and the inclined groove 8 is arranged so that the inner end in the tire width direction precedes the outer end in the tire width direction and enters the tread portion ground contact surface. It is preferable to install. That is, in the embodiment shown in FIGS. 2 and 3, it is preferable that the rotation direction is specified so as to enter the ground plane in order from the upper side of the drawing. Thereby, since an inclined groove follows the input from the road surface at the time of cornering, the lightness of handling performance improves.

  When the tire according to the present invention is mounted on the front wheel of a motorcycle, the lightness of handling performance and the improvement of stability performance during braking are particularly remarkable. This is because, in a motorcycle, the front wheels mainly contribute to handling performance and stability performance.

  Note that the above description shows only a part of the embodiment of the present invention, and these configurations can be combined with each other or various modifications can be made without departing from the gist of the present invention. . For example, the circumferential groove 7 may extend continuously in the tire circumferential direction as shown in FIGS. 2 and 3, but can also be extended intermittently as shown in FIG. When the circumferential groove 7 is interrupted, the ground contact area of the side region 10 is increased, so that grip performance can be improved as compared with the case where the circumferential groove 7 is continuous.

  Next, tires according to the present invention were prototyped and performance evaluations were performed, which will be described below.

  The tire of the example is a motorcycle tire having a tire size of 125 / 600R17, has the tread pattern shown in FIG. 2, and half of the inclined grooves extend beyond the tire equatorial plane.

  For comparison, tires having the tread pattern shown in FIG. 5 (conventional example 1), FIG. 6 (conventional example 2), and FIG. And made a prototype.

  Each of the test tires was assembled on an MT 3.50 rim to form a tire wheel, which was attached to the front wheel of a test motorcycle, and 150 kPa (relative pressure) was applied as the tire internal pressure. A conventional tire having a tire size of 165 / 625R17 was attached to the rear wheel, and 150 kPa (relative pressure) was applied as the tire internal pressure.

  A professional rider sported a circuit on a paved road with this test motorcycle, and evaluated the lightness and stability of handling performance at that time. The evaluation results are shown in Table 1. In addition, the value of the evaluation result in Table 1 is represented by an index in which a numerical value of 100 or more is a satisfactory level and a numerical value less than 100 is a dissatisfied level. The larger the numerical value, the better the performance.

  From the results shown in Table 1, the tires of Conventional Example 1 are dissatisfied with the handling performance in the small to medium camber region, and the tires of Conventional Example 2 and are dissatisfied with the stability performance. It was impossible to achieve both performance and stability. On the other hand, in the tires of the examples, both the handling performance and the stability performance in the small to medium camber region and the medium to large camber region are satisfactory levels, and it can be seen that the tire is excellent in overall performance.

  As is apparent from the above description, the present invention makes it possible to improve the stability during braking while improving the lightness of the handling performance of the pneumatic tire for motorcycles.

1 is a tire width direction sectional view of a typical motorcycle pneumatic tire according to the present invention. It is a partial development view showing a pattern of a typical tread portion of the tire of the present invention. It is a partial development view showing a pattern of another tread portion of the tire of the present invention. It is a partial development view showing a pattern of another tread portion of the tire of the present invention. It is a partial expanded view which shows the pattern of the tread part of the tire of a prior art example. It is a partial expanded view which shows the pattern of the tread part of the tire of a prior art example. It is a partial expanded view which shows the pattern of the tread part of the tire of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire 5 Tread part 7 Circumferential groove 8 Inclined groove 9 Central area of tread part 10 Side area of tread part CL Tire equatorial plane

Claims (8)

At least a pair of circumferential grooves extending substantially in the tire circumferential direction on the tread portion and sandwiching the tire equatorial plane, and the tire circumferential direction from the tire width direction outer side of the tread portion grounding surface toward the tire width direction inner side In a pneumatic tire for a motorcycle that includes a plurality of inclined grooves extending in an inclined direction and terminating in the tread surface.
When the tread portion is divided into a central region and two lateral regions located on both sides of the tread portion, the circumferential groove is located only in the lateral region,
Inclined grooves inclined in the opposite direction to the tire circumferential direction are alternately arranged along the tire circumferential direction,
The inclined grooves that incline in the same direction with respect to the tire circumferential direction are viewed in the tire circumferential direction, the circumferential grooves are crossed, and the inclined grooves that cross the tire equatorial plane and the inclined grooves that do not cross the circumferential grooves are alternately arranged A pneumatic tire for a motorcycle characterized by being made .   The pneumatic tire for a motorcycle according to claim 1, wherein at least half of the inclined grooves extend beyond the tire equatorial plane.   The pneumatic tire for a motorcycle according to claim 1 or 2, wherein the central region has a width of 10% of a creeping width of a tread portion ground contact surface with a tire equator surface as a center.   The pneumatic tire for a motorcycle according to any one of claims 1 to 3, wherein the circumferential groove is a pair or two pairs.   The pneumatic tire for a motorcycle according to any one of claims 1 to 4, wherein the circumferential groove is located in a region having a width of 30% of a creeping width of a tread portion grounding surface with a tread grounding end as a center. .   The pneumatic tire for a motorcycle according to any one of claims 1 to 5, wherein the inclined groove has a linear or arc-shaped extending shape.   The tire is a directional tire in which a rotation direction at the time of mounting on a vehicle is specified, and the inclined groove enters the tread portion ground contact surface with the inner end in the tire width direction preceding the outer end in the tire width direction. The pneumatic tire for a motorcycle according to any one of claims 6.   The pneumatic tire for a motorcycle according to any one of claims 1 to 7, which is attached to a front wheel of the motorcycle.

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